POS0340 PROGNOSTIC FACTORS OF INTERSTITIAL LUNG DISEASE: A 10-YEAR LONGITUDINAL COHORT ANALYSIS
Authors: K. Nakamura, S. Shimoyama, N. Abe, T. Horita
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Interstitial lung disease (ILD), defined as interstitial pneumonia (IP) and pulmonary fibrosis, has a variety of backgrounds. Connective tissue diseases (CTD) is one of the leading causes of ILD, and the concept of "IP with an autoimmune feature (IPAF)" has been established [1]. It has been reported that CTD-related ILD (CTD-ILD) and IPAF have a better prognosis than idiopathic pulmonary fibrosis [2]. However, prognostic differences and factors among CTD-ILD, IPAF, and other ILDs (OILD) remain unknown. <h3>Objectives</h3> This study aimed to analyze the prognosis and its factors in patients with CTD-ILD and IPAF compared to those with OILD. <h3>Methods</h3> We retrospectively collected data from 642 patients diagnosed as "IP" or "pulmonary fibrosis" between 2010 and 2021 at Tomakomai City Hospital. ILD diagnosis was performed by CT scan with 2 rheumatologists. We classified ILD into 3 groups of CTD-ILD, IPAF, and OILD. Mortality and prognostic factors were assessed using Kaplan-Meier methods and Cox proportional hazards models. In addition, we analyzed hospitalization free survival using Kaplan-Meier methods. <h3>Results</h3> Clinical characteristics of the patients are shown in Table 1. The CTD-ILD and IPAF patients were younger, and less frequently complicated by coronary artery disease and chronic heart failure. In addition, more patients in the IPAF and CTD-ILD groups showed a Non-specific interstitial pneumonia (NSIP) pattern on initial CT, while OILD group showed a usual interstitial pneumonia (UIP) and diffuse alveolar damage (DAD) pattern. C-reactive protein (CRP) levels were lower in the IPAF and CTD-ILD group. The prognosis of CTD-ILD and IPAF group was better than OILD group (Figure1, adjusted p&lt;0.001, &lt;0.01, respectively), but that of CTD-ILD and IPAF was similar (adjusted p=1.0). Multivariate analysis revealed the ILD classification was not independent prognostic factor (p=0.11, Hazard ratio (HR) 0.85, [0.70-1.04]). However, age (p&lt;0.001, HR1.03, [1.02-1.05]), sex (p&lt;0.001, HR 2.08, [1.51-2.87]), initial CT patterns as UIP (p&lt;0.01, HR 2.68, [1.27-5.67]) and DAD (p&lt;0.001, HR 7.99, [3.85-16.60]) were independent prognostic factors. The leading causes of death (CTD-ILD vs. IPAF vs. OILD) were IP (48.2% vs. 55.6% vs. 44.7%, p=0.05), infection (10.8% vs. 22.2% vs. 18.4%, p = 0.07), and malignancy (24.1% vs. 5.6% vs. 7.9%, p = 0.03). In the analysis of event free survival, there was no difference among three groups (p =0.80), and the most common cause was the infection in the CTD-ILD group (36.1%) and primary disease in the OILD and IPAF groups (29.0%, 36.4%, respectively). <h3>Conclusion</h3> Unexpectedly, complication of autoimmune features was not a prognostic predictor of ILD. Age, sex, initial CRP level and CT patterns such as UIP and DAD, at the initial diagnosis were critical prognostic factors. <h3>References</h3> [1]Ligia Fernandes, et al. Front Med. 2019 Sep 27;6:209. [2]Jeong Uk Lim, et al. BMC Pulm Med.2019 Jul 4;19:120 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.